JP2002246453A - Method of detecting adhesion of particles to electrostatic suction stage, method of determining necessity of cleaning of electrostatic suction stage, and substrate processing apparatus - Google Patents

Abstract

(57) Abstract: Provided is a practical configuration for determining whether or not cleaning of an electrostatic suction stage is necessary in a substrate processing apparatus that performs processing while sucking a substrate onto an electrostatic suction stage. When a substrate 9 is processed while electrostatically adsorbing a substrate 9 on an electrostatic adsorption stage 4 in a processing chamber 1, a detection gas introduction system 71 is inserted into a gap between the electrostatic adsorption stage 4 and the substrate 9.
To introduce a detection gas. By measuring the pressure in the gas introduction path of the detection gas with the pressure gauge 72, the change in the conductance of the gap between the electrostatic suction stage 4 and the substrate 9 is known. Thereby, the adhesion of the particles to the electrostatic attraction stage 4 is detected, and it is determined whether or not the surface of the electrostatic attraction stage 4 needs to be cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing apparatus used in the manufacture of a semiconductor device such as an LSI, and more particularly to a technique for processing a substrate while adsorbing the substrate on an electrostatic adsorption stage.

[0002]

2. Description of the Related Art Semiconductor devices such as LSIs are manufactured through many surface treatments for substrates. An apparatus for performing such processing often includes an electrostatic suction stage in order to hold a substrate at a predetermined position during processing. FIG.
FIG. 1 is a schematic front view showing a conventional substrate processing apparatus provided with such an electrostatic suction stage. FIG. 8 shows a schematic configuration of a sputtering apparatus as an example.

[0003] The apparatus shown in FIG. 8 includes a processing chamber 1 provided with an exhaust system 11, a process gas introduction system 2 for introducing a predetermined gas into the processing chamber 1, and a processing chamber 1.
Target 3 provided with a surface to be sputtered exposed inside
1 and applying a voltage to the target 31
Power supply 32 for sputtering the target and an electrostatic suction stage 4 for disposing the substrate 9 at a position in the processing chamber 1 where a material (hereinafter, sputtered particles) released from the target 31 by the sputtering reaches. .

When a voltage is applied to the target 31 by a sputtering power supply 32 while a predetermined gas is being introduced by the process gas introduction system 2, a sputter discharge occurs and the target 31 is sputtered. The sputtered particles emitted from the target 31 by the sputtering reach the surface of the substrate 9 and a thin film made of the material of the target 31 is formed.

The electrostatic attraction stage 4 includes a dielectric block 41 made of a dielectric and a pair of attraction electrodes 42 provided in the dielectric block 41. And
An adsorption power supply 43 for applying a DC voltage to the adsorption electrode 42 is provided. When a DC voltage is applied to the adsorption electrode 42,
Dielectric polarization of the dielectric block 41 induces static electricity on the surface. The substrate 9 is electrostatically attracted by the static electricity.

[0006]

It is one of the most important problems required for the above-mentioned substrate processing apparatus to perform high-quality processing on the substrate. Factors affecting the processing quality include the presence of particles. The term particle is used herein to generically refer to substances that contaminate the substrate or impair the quality of the processing. Therefore, it is not necessarily limited to a particulate substance. For example, in a substrate processing apparatus using an electrostatic attraction stage, since the substrate is pressed against the electrostatic attraction stage by static electricity, the back surface of the substrate may be damaged by irregularities on the surface of the electrostatic attraction stage. When the back surface of the substrate is damaged, fragments of the peeled substrate material become fine particles and float in the processing chamber. If the fine particles adhere to the surface of the substrate, an abnormality such as a short circuit may occur, and the fine particles are particles.

In addition, in an apparatus for forming a film by sputtering, particles may be generated due to peeling of a thin film deposited on an exposed surface in a processing chamber. In the processing chamber where the film is formed, the thin film is not only on the surface of the substrate,
It is also deposited on exposed surfaces such as the inner wall surface of the processing chamber. If the deposition of the thin film on the exposed surface overlaps, the thin film may be peeled off due to internal stress or own weight. The peeled thin film becomes fine particles of a certain size and floats in the sputtering chamber. When the fine particles adhere to the substrate, there is a possibility that a shape defect such as formation of minute projections on the thin film on the substrate or a defect such as disconnection or short circuit of the circuit may occur. Therefore, these fine particles are also particles.

In some cases, particles are brought into the processing chamber by the substrate itself. For example, particles may adhere to the back surface of the substrate in another processing chamber or outside the apparatus (in the air), and the substrate may be carried into the processing chamber in that state, so that the particles may be brought into the processing chamber. Furthermore, in a vapor deposition apparatus (CVD apparatus) utilizing a gas phase reaction, particles may be generated in the processing chamber due to unreacted products or residual gas. In an apparatus that performs etching, a material released from a substrate by etching may remain in a processing chamber and become particles.

As described above, such particles cause a serious problem when they adhere to the surface of the substrate. However, when they adhere to the surface of the electrostatic attraction stage, they do not cause a serious problem. However, if the particles adhere to the electrostatic chuck stage and the particles are clumped to a certain size, a problem arises in that the clumps of the substrate are not sufficiently absorbed by the clumps. In other words, the lump may cause the substrate to float from the electrostatic suction stage, resulting in displacement. If the displacement occurs, the operation of removing the substrate from the electrostatic suction stage cannot be performed well, and a transport error may occur.

Particularly, there is a case where the electrostatic chuck stage also has a function of controlling the temperature of the substrate and has a mechanism for heating or cooling the substrate. If the substrate is lifted from the electrostatic suction stage by the lump of particles, heat transfer between the substrate and the electrostatic suction stage becomes insufficient. As a result, the substrate cannot be sufficiently heated or cooled, resulting in a temperature control failure. Furthermore, the particles that have become large chunks may be crushed by the impact of the substrate being placed on the electrostatic suction stage. At this time, a large amount of lump fragments are released, and a large amount of particles are generated suddenly, which greatly increases the possibility of the particles adhering to the surface of the substrate. Incidentally, there is a case where a layer of foreign matter is formed on the surface of the electrostatic suction stage due to the adhesion of the particles. If such a layer is formed, it may be impossible to normally perform electrostatic adsorption and temperature control.

[0011] In order to solve the problem caused by the adhesion of particles to the electrostatic chuck stage, the surface of the electrostatic chuck stage is periodically cleaned. Cleaning is described in JP-A-2000-269313.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, in many cases, this is performed by bombarding particles by bombarding the surface of the electrostatic suction stage with ions.

Since such cleaning is not directly related to the processing of the substrate, it is preferable to minimize the cleaning. However, in the conventional configuration, it is difficult to determine the timing at which cleaning is required, so that cleaning may be performed more than necessary, or cleaning may not be performed when necessary. More specifically, it is most elaborate and ideal that the cleaning be performed before the substrate is attracted to the electrostatic attraction stage in each processing, but it is not necessary, and if so, the productivity is increased. Is significantly reduced. Therefore, the number of times of processing leading to a problem such as a decrease in electrostatic attraction force or a large number of particles is determined, and cleaning is performed before the number of times of processing is reached.

However, the contents of the processing are not always the same. The gas used for the processing is different, the discharge conditions for forming the plasma are different, and the pressure in the processing chamber is different. Also, the substrates to be processed are not always in the same state. The state of the front surface of the substrate also differs depending on what kind of processing is performed in the previous process, and whether particles may adhere to the back surface of the substrate in the previous process also differs depending on the content of the processing in the previous process. Come. Therefore, how many times the process is repeated may cause a problem such as a decrease in the electrostatic attraction force or a large amount of particles, or it may vary depending on the content of the process and the state of the substrate at that time, and is not constant. And it is extremely difficult to predict it in advance.

For this reason, the cleaning is performed in a cycle shorter than necessary, and the productivity is meaninglessly reduced. On the contrary, the cleaning cycle becomes too long, and the electrostatic attraction force is reduced. Problems such as reduction and large number of particles are likely to occur. The invention of the present application has been made to solve such a problem, and in a substrate processing apparatus that performs processing while adsorbing a substrate on an electrostatic adsorption stage, it is practical to determine whether or not cleaning of the electrostatic adsorption stage is necessary. There is a technical significance of providing a configuration.

[0015]

According to an aspect of the present invention, there is provided a substrate processing apparatus for performing a predetermined process on a substrate in a processing chamber. A method for detecting adhesion of particles to an electroadhesion stage, wherein the adhesion of particles is detected from a change in the conductance of a gap between the electrostatic adsorption stage and the substrate when the substrate is electrostatically adsorbed to the electrostatic adsorption stage. Having. According to a second aspect of the present invention, there is provided a substrate processing apparatus for performing a predetermined process on a substrate in a processing chamber, wherein adhesion to an electrostatic suction stage provided in the processing chamber is reduced. The structure is such that it is determined from the change in the conductance of the gap between the electrostatic suction stage and the substrate when the substrate is electrostatically sucked on the electro-suction stage, and it is determined whether or not the surface of the electrostatic suction stage needs to be cleaned. In order to solve the above-mentioned problem, the invention according to claim 3 is the configuration according to claim 1 or 2, wherein the detection is performed in a gap between the substrate and the electrostatic suction stage that are sucked by the electrostatic suction stage. It has a configuration in which a change in the conductance is known by introducing a gas and measuring the pressure in the gap or the gas introduction path of the detection gas. Also, in order to solve the above problems,
According to a fourth aspect of the present invention, in the configuration of the third aspect,
The change in the conductance is known by introducing the detection gas so that the pressure in the gap or the gas introduction path is kept constant, and comparing the number of repetitions of introduction and shutoff or the total introduction amount at that time. It has the structure of. According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, in the configuration of the third aspect, a predetermined amount of the detection gas is introduced into the gap, and the pressure in the gap or the gas introduction path is set to a predetermined value. The change in the conductance is known by comparing the time required for the pressure to drop to the lower limit of the pressure. According to another aspect of the present invention, a processing chamber evacuated by an exhaust system, a gas introduction system for introducing a predetermined processing gas into the processing chamber, and a substrate to be processed are statically solved. A substrate processing apparatus comprising: an electrostatic suction stage that is electro-adsorbed and held at a predetermined position in a processing chamber, wherein a gap between the substrate and the electrostatic suction stage that is sucked by the electrostatic suction stage is formed. A configuration is provided in which a detection unit that detects adhesion of particles to the electrostatic suction stage from a change in conductance is provided. According to a seventh aspect of the present invention, in the configuration of the sixth aspect, the detecting means includes a gap between the substrate and the electrostatic suction stage which are sucked by the electrostatic suction stage. A detection gas introduction system for introducing a detection gas to the pressure sensor, a pressure gauge for measuring a pressure in a gap or a gas introduction path of the detection gas introduction system, and a comparison unit for comparing a measured value of the pressure gauge with a predetermined reference value. And a configuration that consists of Further, in order to solve the above-mentioned problem, the invention according to claim 8 is the same as the above claim. In the configuration, the processing chamber evacuated by the exhaust system, the gas introduction system for introducing a predetermined processing gas into the processing chamber, and the substrate to be processed are electrostatically attracted and held at a predetermined position in the processing chamber. And a cleaning means for cleaning the surface of the electrostatic suction stage, wherein a gap between the substrate and the electrostatic suction stage that is suctioned by the electrostatic suction stage is provided. There is provided a configuration in which a determination unit that determines whether or not cleaning by the cleaning unit is necessary is provided based on a change in conductance. In order to solve the above problem, according to the ninth aspect of the present invention, in the configuration of the eighth aspect, the determining means is configured to determine a gap between the substrate and the electrostatic attraction stage that are attracted to the electrostatic attraction stage. A detection gas introduction system for introducing a detection gas to the pressure sensor, a pressure gauge for measuring a pressure in a gap or a gas introduction path of the detection gas introduction system, and a comparison unit for comparing the measured value of the pressure gauge with a predetermined reference value And a configuration that consists of Further, in order to solve the above-mentioned problem, the invention according to claim 10 is, in the structure of claim 7 or 9, provided with a controller that controls the detection gas introduction system, and the controller is configured to control the gap or The detection unit controls the gas introduction system for detection so that the pressure in the gas introduction path is kept constant, and the comparison unit performs the number of repetitions of introduction and cutoff of the detection gas or the total introduction amount at that time. Are compared. Further, in order to solve the above problem, according to the invention of claim 11, in the configuration of claim 7 or 9, a controller for controlling the detection gas introduction system is provided, and the controller is provided in the gap. The detection unit controls the gas introduction system for detection so that a certain amount of the gas for detection is introduced, and the comparison unit performs a process until the pressure in the gap or the gas introduction path decreases to a predetermined pressure lower limit. It is configured to compare time. According to a twelfth aspect of the present invention, in the above configuration, the detection gas introduced by the detection gas introduction system is the electrostatic suction stage. It is also used as a heat exchange gas for improving the heat exchange efficiency between the substrate and the substrate.

[0016]

Embodiments of the present invention (hereinafter, embodiments) will be described below. FIG. 1 is a schematic front view of a substrate processing apparatus according to a first embodiment of the present invention. FIG. 1 shows a configuration of a sputtering apparatus as an example of a substrate processing apparatus, similarly to the apparatus shown in FIG.

The apparatus shown in FIG. 1 includes a processing chamber 1 evacuated by an exhaust system 11, a process gas introducing system 2 for introducing a predetermined gas into the processing chamber 1, and a sputtered surface in the processing chamber 1. An exposed target 31, a sputter power supply 32 for applying a voltage to the target 31 to sputter the target 31, and a substrate 9 at a position in the processing chamber 1 to which sputtered particles emitted from the target 31 by sputtering reach. And an electrostatic suction stage 4 for arranging them.

The exhaust system 11 is equipped with a vacuum pump such as a cryopump or the like so as to be able to exhaust the inside of the processing chamber 1 to a pressure of about 10 ⁻⁸ Torr (or 10 ⁻⁶ Pa). The process gas introduction system 2 is configured so that a gas such as argon having a high sputtering rate can be introduced into the processing chamber 1 at a predetermined flow rate.

The target 31 is attached to the processing chamber 1 via an insulating material 311. The sputtering power source 32 supplies a negative DC voltage or a high-frequency voltage to the target 31.
To be applied. Behind the target 31 (on the side opposite to the surface to be sputtered), a magnet mechanism 33 is provided. The magnet mechanism 33 includes the center magnet 331 and the center magnet 3
And a ring-shaped peripheral magnet 332 surrounding the base 31. Electrons are confined in the magnetic field set by the magnet mechanism 33, and high-efficiency sputtering can be performed.

The electrostatic suction stage 4 includes a metal stage body 40, a dielectric block 41 fixed to the stage body 40, and a pair of suction electrodes 42 provided in the dielectric block 41. I have. Further, a suction power source 43 for applying a DC voltage to the suction electrode 42 is provided to induce static electricity on the surface of the dielectric block 41 to electrostatically hold the substrate 9.

A heater 44 is provided inside the stage body 40 made of metal. The heater 44 is of a resistance heating type that generates Joule heat when energized. A radiant heating type such as an infrared lamp can also be used as the heater 44. The stage main body 40 and the dielectric block 41 are joined with good thermal contact, and heat from the heater 44 is transmitted to the substrate 9 via the dielectric block 41.
The heater 44 is controlled by a heater power supply (not shown),
As a result, the substrate 9 is heated and maintained at a predetermined temperature.

The apparatus according to the present embodiment includes an electrostatic attraction stage 4
Cleaning means for cleaning the surface of the device. The cleaning means cleans the surface of the electrostatic suction stage 4 by bombarding it with ions.
More specifically, the cleaning unit includes a high-frequency power supply 51 and the like, forms plasma by high-frequency discharge in a space facing the electrostatic chucking stage 4, and cleans the surface of the electrostatic chucking stage 4 with ions in the plasma. It is shocking.

The high frequency power supply 51 is connected to the electrostatic suction stage 4 via a matching circuit 52 and a variable capacitor 53. The high-frequency power supply 51 supplies a high-frequency voltage to the attraction electrode 42 so as to be superimposed on the DC voltage of the attraction power supply 43. That is,
The transmission line from the high frequency power supply 51 is connected to a line connecting the suction power supply 43 and the electrostatic suction stage 4.

When a high-frequency voltage is applied to the attraction electrode 42, a high-frequency electric field is set in a space facing the electrostatic attraction stage 4. The set high-frequency electric field gives energy to the gas introduced by the process gas introduction system 2 and turns the gas into plasma. The surface of the electrostatic adsorption stage 4 is bombarded with ions in the plasma, and attached particles are repelled.

A filter circuit 45 is provided on a line closer to the adsorption power supply 43 than a connection point of the transmission line from the high frequency power supply 51.
Is provided. The filter circuit 45 is for preventing a high frequency wave from flowing toward the suction power supply 43 and damaging the suction power supply 43. Note that it is preferable to control the incident energy of the ions so that the surface of the electrostatic suction stage 4 is not shaved by the ions that impact the electrostatic suction stage 4. This control can be performed by adjusting the magnitude of the self-bias voltage applied to the electrostatic attraction stage 4 by the interaction between the plasma and the high frequency.

When a high frequency voltage is applied to the electrostatic attraction stage 4 to form plasma, if an appropriate capacitance exists between the electrostatic attraction stage 4 and the high frequency power supply 51,
The self-bias voltage is applied to the electrostatic suction stage 4 by the interaction between the high frequency and the plasma. The self-bias voltage is a negative DC component voltage superimposed on a high frequency.

The self-bias voltage has a function of extracting positive ions in the plasma and reaching the electrostatic attraction stage 4. The magnitude of the self-bias voltage can be adjusted by adjusting the magnitude of the capacitance, and the electrostatic attraction stage 4 can be adjusted without shaving the surface of the electrostatic attraction stage 4.
It is possible to control the incident energy of the ions so as to bounce off the particles existing on the surface. For example, when the surface of the electrostatic suction stage 4 is made of alumina,
The magnitude of the self-bias voltage is -200V to -500V
Degree. The variable capacitor 53 shown in FIG. 1 is controlled so as to have such a self-bias voltage.

Further, as shown in FIG. 1, a deposition shield 6 is provided inside the inner surface of the processing chamber 1. The anti-adhesion shield 6 prevents particles on the surface of the electrostatic suction stage 4 that have been repelled by the above-described plasma from adhering to the inner surface of the processing chamber 1. Without the deposition shield 6, particles adhere to the inner surface of the processing chamber 1. Then, there is a possibility that it is separated by its own weight or the like, floats again in the processing chamber 1, and adheres to the substrate 9. The protection shield 6 prevents this problem.

The deposition shield 6 is used for preventing the sputtered particles flying during the sputter deposition on the substrate 9 from the processing chamber 1.
It also prevents it from reaching the inside of the car. When such sputtered particles adhere, the sputtered particles grow into a thin film. When the film thickness reaches a certain level, the film is peeled off due to internal stress or the like and becomes a source of particles. Shield 6
Is a cylindrical member having a shape surrounding a space between the electrostatic suction stage 4 and the target 31. Shield 6
Is subjected to a surface treatment so as not to be easily peeled off even if particles adhere or a thin film is deposited. The deposition shield 6 is provided in the processing chamber 1 in a replaceable state.

A significant feature of the substrate processing apparatus shown in FIG. 1 is that a judgment means for judging the necessity of cleaning by the cleaning means is provided. The judgment means is
The necessity of cleaning is determined from the change in the conductance of the gap between the substrate 9 sucked on the electrostatic suction stage 4 and the electrostatic suction stage 4.

More specifically, the judging means comprises: the substrate 9 attracted to the electrostatic attraction stage 4 and the electrostatic attraction stage 4
And a pressure gauge 72 for measuring a pressure in a gas introduction path of the detection gas introduction system 71, and a measured value of the pressure gauge 72 is compared with a predetermined reference value. It is mainly composed of a comparison unit.

As shown in FIG. 1, the electrostatic suction stage 4
Has a through passage 46 extending vertically. Penetration 46
Reaches the upper surface on which the substrate 9 is placed, and the detection gas introduction system 71 introduces a gas between the substrate 9 and the electrostatic suction stage 4 via the through-path 46. Has become. Although any gas can be used as the detection gas to be introduced, argon is used in the present embodiment.
This also has the meaning of reducing equipment costs by introducing the same gas as in the process gas introduction system 12. Also, by introducing the same gas as in the process gas introduction system 2, there is also a purpose of facilitating exhaustion by the exhaust system 11.

The detection gas introduction system 71 has a valve 711 on a pipe connected to the through passage 46 of the electrostatic suction stage 4. The valve 711 is for introducing or shutting off the detection gas. The pressure gauge 72 has a valve 711.
The pressure in the pipe between the and the electrostatic suction stage 4 is directly measured. The pressure in this portion may be equal to the pressure in the gap between the substrate 9 and the electrostatic suction stage 4. As the pressure gauge 72, a diaphragm (diaphragm) pressure gauge is employed. Note that, in the present embodiment, the “gas introduction path” simply means a path for introducing a gas, and includes a case of a through path 46 provided in the electrostatic suction stage 4 as shown in FIG. Includes cases such as spaces inside.

The apparatus according to the present embodiment includes a controller 8 for controlling each unit. The measurement value of the pressure gauge 72 is sent to the controller 8 via an AD converter (not shown). Also, the valve 7 of the detection gas introduction system 71
The opening and closing of 11 is also controlled by the controller 8. In addition, the controller 8 controls the exhaust system 11, the process gas introduction system 2, the sputtering power supply 32, the high-frequency power supply 51, and the like.

The controller 8 has a computer unit 81, an input / output port 82, and the like. The computer unit 81 includes a processor 81 such as an MPU.
1 and a storage unit 812 such as a memory such as a ROM or a RAM or a hard disk. In the storage unit 812 of the computer unit 81, a sequence control program for operating each unit of the device at an appropriate timing is installed.

Next, the operation of the substrate processing apparatus according to the present embodiment having the above configuration will be described, also serving as the description of the embodiments of the inventions of the first to fifth aspects. First, the substrate 9 is carried into the processing chamber 1 through a gate valve (not shown), and is placed on the electrostatic suction stage 4. The controller 8 operates the heater 44 in the electrostatic suction stage 4 in advance, and the heat of the heater 44 is transmitted to the substrate 9. The controller 8 operates the attraction power supply 43 to apply a DC voltage to the pair of attraction electrodes 42 to dielectrically polarize the dielectric block 41. As a result, the substrate 9 is electrostatically attracted to the electrostatic attraction stage 4.

The controller 8 operates the exhaust system 11 in advance to exhaust the processing chamber 1 to a predetermined vacuum pressure. After loading the substrate 9, the controller 8 closes the gate valve and operates the process gas introduction system 2. The controller 8 controls the flow regulator (not shown) provided in the process gas introduction system 2 to operate the sputtering power supply 32 while adjusting the amount of gas introduced into the gas processing chamber 1. As a result, the target 31 is sputtered,
The sputtered particles reach the substrate 9 and a desired thin film is formed on the surface of the substrate 9.

The controller 8 continues the sputtering for a predetermined time to form a thin film of a predetermined thickness.
2 and the operation of the process gas introduction system 2 are stopped to stop sputtering. Then, the controller 8 stops the operation of the suction power supply 43 and releases the electrostatic suction. Next, the controller 8 controls the processing chamber 1 by the exhaust system 11.
After evacuating the inside again, open the gate valve. And
The substrate 9 is carried out of the processing chamber 1 by a transfer system (not shown). By repeating such an operation, the substrate 9
Is carried into the processing chamber 1 to perform a film forming process.

In the above operation, the controller 8 causes the detection gas introduction system 71 to perform gas introduction for determining whether or not the electrostatic suction stage 4 is necessary. Further, in the storage unit 812 of the computer unit, a necessity determination program for determining necessity of cleaning according to the data sent from the pressure gauge 72 is installed. The comparison unit of the determination unit in the present embodiment is configured by the necessity determination program and the computer unit 81. These points will be described with reference to FIGS. FIG. 2 shows a portion of the sequence control program executed by the controller 8 for extracting the detection gas. FIG. 3 is a diagram showing a sequence of the detection gas introduction and a transition of the measurement value of the pressure gauge 72.

As shown in FIG. 2, after confirming that the substrate 9 has been electrostatically attracted to the electrostatic attraction stage 4, the controller 8 opens the valve 711 of the detection gas introduction system 71.
The detection gas introduction system 71 has a flow regulator (not shown), and the controller 8 controls the flow regulator in advance so that the gas flow rate becomes a predetermined value. At the same time as the introduction of the detection gas is started, a signal from the pressure gauge 72 is always input. With the start of the introduction of the detection gas, the sequence control program substitutes 1 for a memory variable for the number of introductions (hereinafter, a number memory variable).

After the introduction of the detection gas, as shown in FIG.
The measured value of the pressure gauge 72 is compared with a preset pressure upper limit value. If the measured value is lower than the upper pressure limit, the introduction of the detection gas is continued. When the measured value from the pressure gauge 72 further increases and becomes equal to or larger than the upper pressure limit, the controller 8 closes the valve 711 of the detection gas introduction system 71 and stops the introduction of the detection gas.

The gap between the electrostatic suction stage 4 and the substrate 9 shown in FIG. 1 is not completely closed, and the introduced detection gas leaks out of the gap little by little. Therefore, as shown in FIG. 3, after the introduction of the detection gas is stopped, the measured value of the pressure gauge 72 gradually decreases. And FIG.
As shown in (2), when it is determined that the measured value is lower than the upper pressure limit, the controller 8 opens the valve 711 again and restarts the introduction of the detection gas. With the restart, (count memory variable + 1) is substituted for the count memory variable.

The processing time for one substrate 9 (hereinafter, referred to as the processing time)
During the above process, the introduction and the stop of the detection gas are repeated so that the measured value is maintained at the upper pressure limit. Then, the count memory variable is updated with a value obtained by adding 1 each time the introduction of the detection gas is restarted. In the program shown in FIG. 2, when the process time ends, the process exits from the loop and the program of this portion ends.

When the processing for one substrate 9 is completed in this way, the controller 8 determines whether or not cleaning is necessary. The sequence control program has the above-described necessity determination program as a subroutine.
FIG. 4 shows a portion of a necessity determination program which is a subroutine in the sequence control program executed by the controller 8.

As shown in FIG. 4, after confirming that the processing of the substrate 9 has been completed and the substrate 9 has been unloaded from the processing chamber, the number-of-times memory variable is called. Then, the called count memory variable is compared with the count upper limit value. The upper limit of the number of times is a reference value that is determined to require cleaning if the number of times exceeds the upper limit, and is set in advance.

When the number-of-times memory variable exceeds the number-of-times upper limit value, the controller 8 executes a sequence control for performing cleaning. After the cleaning, the carrying-in operation of the next substrate 9 is performed, and the sequence control is performed so that the processing for the next substrate 9 is similarly performed. If the number-of-times memory variable is equal to or smaller than the number-of-times upper limit value, the cleaning is not performed and the next substrate 9 is carried in and the process is performed.

The grounds for judging the necessity of cleaning in accordance with the value of the number-of-times memory variable will be further described with reference to FIGS. 1, 3 and 5. FIG. 5 is a diagram illustrating a change in conductance due to the attachment of particles. The back surface of the substrate 9 and the surface of the electrostatic suction stage 4 are not completely flat surfaces but have minute irregularities. Therefore, FIG.
As shown in FIG. 5, even if the substrate 9 is attracted to the electrostatic attraction stage 4, there is a small gap between the two, and the introduced detection gas leaks little by little as described above (FIG. 5). (1)). Then, when the particles 100 adhere and the height thereof becomes sufficiently higher than the irregularities on the surface of the electrostatic suction stage 4, the substrate 9 is lifted by the particles 100 as shown in FIG. State. In this state, the conductance of the gap between the substrate 9 and the electrostatic attraction stage 4 rapidly increases.

When the conductance is small as shown in FIG. 5A, the amount of leakage when the detection gas is introduced is also small.
Therefore, as shown in FIG. 3A, the total number of times of introduction and cutoff of the detection gas within the process time is small. That is, the value of the number-of-times memory variable at the end of the process is also small. on the other hand,
When the conductance is large as shown in FIG.
The leakage amount of the detection gas also increases. Therefore, FIG.
As shown in (1), the total number of times of introduction and cutoff of the detection gas within the process time increases. That is, the number-of-times memory variable at the end of the process increases. If a problematic amount of particles adheres, the value of the number-of-times memory variable at the end of the processing can be experimentally checked in advance. If a value slightly lower than this value is set as the number-of-times upper limit value, in the actual processing of the substrate 9, if the number-of-times memory variable reaches the number-of-times upper limit value, it can be determined that cleaning is necessary.

Incidentally, whether or not a problematic amount of particles has adhered can be determined from the total gas introduction amount within the process time. As this configuration, for example, a program is provided in which the gas flow rate in the detection gas introduction system 71 is made constant and the controller 8 integrates the gas flow time. Then, the total gas flow rate within the process time is calculated and compared with the reference value. When the conductance increases due to the adhesion of the particles, the total gas flow rate also increases. Therefore, the adhesion of the particles can be detected by comparing with an appropriate reference value.

Next, the cleaning operation will be described in more detail. When performing cleaning, the controller 8 causes the exhaust system 11 to exhaust the inside of the processing chamber 1 again after unloading the substrate 9 from the processing chamber. When the gas is exhausted to a predetermined vacuum pressure, the controller 8 operates the process gas introduction system 2 to introduce an argon gas at a predetermined flow rate. Next, the controller 8 operates the high-frequency power supply 51 constituting the cleaning unit, and forms plasma by high-frequency discharge as described above. At this time, the controller 8 controls the variable capacitor 53 to apply an optimal self-bias voltage to the electrostatic suction stage 4. Thereby, ions in the plasma are extracted, and the surface of the electrostatic suction stage 4 is bombarded with the ions. By ion bombardment,
Particles adhering to the surface are ejected. At this time, the incident energy of the ions is controlled so that the surface of the electrostatic suction stage 4 is not shaved by the ions.

After such cleaning, normal processing is resumed, but an operation called a dummy run may be performed before resuming. The dummy run is performed on the substrate 9 without performing the processing.
, Suction to the electrostatic suction stage 4, unloading of the substrate 9,
Is repeated a predetermined number of times (number of sheets).
In some cases, a dedicated dummy substrate is used. Such operations are repeated, and after confirming that electrostatic attraction and transport are performed correctly, normal processing is resumed. In addition, if an electrostatic suction failure or a transport error occurs during the dummy run, cleaning is performed again.

According to the apparatus of the present embodiment having the above-described configuration and operation, the amount of particles that require cleaning is automatically detected, so that cleaning can be appropriately performed according to the detection result. . Therefore,
There is a problem that cleaning is performed in an unnecessarily short cycle and the productivity is reduced meaninglessly, and conversely, the cleaning cycle becomes too long, and the electrostatic attraction force is reduced and a large number of particles are generated. It does not cause it. Although the comparison between the measured value of the pressure gauge 72 and the pressure upper limit value has been described as being performed by software, the comparison may be performed by hardware such as a comparison by an operational amplifier. In this case, the comparison unit of the determination unit is configured by hardware such as an operational amplifier.

Next, a second embodiment of the present invention will be described. The substrate processing apparatus according to the second embodiment is different only in the sequence control program executed by the controller 8. Therefore, other description is omitted. FIG.
In the sequence control program provided in the apparatus of the second embodiment, a part for determining whether or not the introduction of the detection gas and the necessity of cleaning is extracted is shown. Also in this embodiment, the comparison section of the determination means is constituted by a part of the sequence control program, and that part is shown in FIG.

FIG. 7 is a graph showing the amount of gas introduced when the detection gas is introduced in accordance with the sequence control program shown in FIG. In the present embodiment, it is assumed that the detection gas is introduced and the necessity of the cleaning is determined each time a predetermined number of substrates 9 are processed (for example, each time 25 substrates are processed in one lot).

After a predetermined number of substrates 9 have been processed, a sequence control program shown in FIG. 6 is executed. First, the controller 8 sucks the substrate 9 onto the electrostatic suction stage 4 while maintaining the inside of the processing chamber 1 at the same pressure as in normal processing. At this time, the substrate 9 is a normal substrate 9
Or a special one for judging the necessity of cleaning. After confirming that the substrate 9 has been electrostatically attracted, the controller 8 introduces a predetermined amount of gas through the detection gas introduction system 71. At this time, the introduction amount is controlled by controlling the introduction time while flowing the gas at a constant flow rate (that is, controlling the time from opening to closing of the valve 711) or determined in a reservoir (not shown). This is done by storing and introducing a quantity of gas.

As shown in FIG. 7, the measured value of the pressure gauge 72 sharply increases after the start of gas introduction, but gradually decreases after the end of gas introduction. As shown in FIG. 6, the sequence control program starts counting up the timer from the start of gas introduction. Then, the measured value of the pressure gauge 72 is compared with the lower pressure limit. As the pressure lower limit, for example, a value substantially equal to the pressure in the processing chamber is set. When it is determined that the measured value has reached the lower pressure limit, the sequence control program ends counting up of the timer, and substitutes the value of the timer at that time into a time memory variable. The time until the measured value reaches the pressure lower limit value is the time during which gas remains in the gap, and is hereinafter referred to as gas remaining time.

Next, the sequence control program compares the value of the time memory variable with the time set value. If the value of the time memory variable is smaller than the time, the time set value is a value at which a large amount of particles adhere and it is determined that cleaning is necessary. More specifically, as shown in FIG. 5A, when the adhesion of the particles 100 is small and the conductance is small, as shown in FIG. 7A, the gas residual time is small because the gas leakage is small. long. On the other hand, FIG.
As shown in (2), when the adhesion of the particles 100 increases and the conductance increases, as shown in FIG. 7 (2), the gas residence time becomes shorter because gas leakage also increases.

Similarly, the value of the gas remaining time when a problematic amount of particles is attached can be experimentally determined in advance. A time slightly exceeding this value is set as a time setting value. In this way, when the value of the time memory variable becomes the time set value in the actual processing of the substrate 9, it can be determined that cleaning is necessary. When it is determined that cleaning is necessary, cleaning is performed as described above. Then, after performing a dummy run as necessary, the processing of the next lot is restarted. It is to be noted that the pressure in the processing chamber 1 and the evacuation speed of the evacuation system 11 need to be kept constant at all times during the experiment for obtaining the time set value in advance and the actual processing of the substrate 9. If the pressure or the pumping speed changes due to a change in the content of the processing or the like, the time set value must be obtained again.

In the configuration of this embodiment, it is difficult to constantly monitor the adhesion of particles while performing normal processing of the substrate 9. More specifically, in the first embodiment, since the detection gas is introduced so as to keep the pressure in the gap between the electrostatic suction stage 4 and the substrate 9 constant, the pressure in the gap is essentially within the process time. Does not fluctuate. However, in the second embodiment, the pressure in the gap greatly changes when detecting the adhesion of particles. If this is performed during the processing of the substrate 9, the pressure in the gap fluctuates greatly during the processing of the substrate 9, and it is difficult to employ this method when strict uniformity in processing conditions over time is required. However, when such a request is not severe, the configuration of the second embodiment can be performed during the processing of the substrate 9.

Incidentally, the second embodiment has an advantage that the consumption amount of the detection gas is small as compared with the first embodiment. Also in this embodiment, the comparison between the value of the time memory variable and the time setting value has been described as being performed by software. However, the comparison may be performed by hardware as in the case of using an operational amplifier. Therefore, the comparison unit of the determination unit may be configured by hardware such as an operational amplifier.

Next, embodiments of the first and sixth aspects of the present invention will be described. In the first and second embodiments,
Although the detection of the change in conductance due to the detection gas is for determining whether or not the electrostatic suction stage 4 needs to be cleaned, it may be configured to detect the adhesion of particles itself. This configuration corresponds to the first or sixth embodiment of the invention.

More specifically, the substrate processing apparatus of this embodiment includes a detecting means for detecting adhesion of particles to the surface of the electrostatic attraction stage 4 from a change in conductance. The detection means comprises a detection gas introduction system 71 and a pressure gauge 72 similar to those of the above-described embodiment, and a comparison unit for comparing the measured value of the pressure gauge 72 with a predetermined reference value. The reference value in the comparison unit is a value that serves as a reference when determining whether or not particles have adhered. The upper limit of the number of times in the above-described first embodiment and the time setting value in the second embodiment correspond to this.

However, a value smaller than the upper limit of the number of times in the first embodiment may be set as the upper limit of the number of times, or a value smaller than the set time of the time in the second embodiment may be set as the set time of the time. . This corresponds to the case where it is necessary to determine that particles have adhered even when the amount of cleaning is not determined to be necessary in the first and second embodiments.

Such a configuration for detecting the adhesion of particles is suitable when the detection of the adhesion of particles is used for purposes other than cleaning by the cleaning means. For example, the case where the electrostatic suction stage 4 is cleaned by means other than the cleaning unit corresponds to this case. When the adhesion of particles is detected, the case where the inside of the processing chamber is opened to the atmosphere and the operator performs manual cleaning corresponds to the case. Further, when the attachment of particles is detected, the processing may be stopped for the time being. In such a case, the configuration of this embodiment can be used.

The configuration for detecting the adhesion of particles based on the change in conductance has the technical significance that it is a simple configuration in which particles in the gap between the substrate 9 and the electrostatic suction stage 4 can be detected on the spot. The adhesion of the particles to the electrostatic attraction stage 4 can be indirectly known from the amount of the particles attached to the back surface of the substrate 9 removed from the electrostatic attraction stage 4. However, this is not the amount of particles actually attached to the electrostatic suction stage 4. Even if the amount of particles attached to the back surface of the substrate 9 is small, a large amount of particles may adhere to the electrostatic suction stage 4.

There is also an apparatus provided with a particle monitor, which mainly detects particles floating in the processing chamber, and does not directly monitor the adhesion of particles to the electrostatic suction stage 4. Absent.
For example, magnify the surface of the electrostatic suction stage 4 for direct observation.
Although there is no way to directly detect the adhesion of particles to the electrostatic suction stage 4 by an optical method,
The configuration tends to be large, and there are also problems such as fogging of the optical window due to gas and residues in the processing chamber 1. In comparison, the configuration of the present embodiment is a simple and extremely practical configuration that can detect the adhesion of particles.

In each of the above-described embodiments, the electrostatic suction stage 4 and the substrate 9
Although a configuration in which a detection gas is introduced into the gap between the two is adopted, other configurations are possible in principle. For example, when the pressure in the processing chamber 1 is kept constant and the exhaust gas is exhausted at a constant exhaust speed through the through passage 46 shown in FIG. It is also possible to know the change. However, since the pressure around the electrostatic suction stage 4 is a vacuum pressure, the change in the exhaust characteristic due to the change in the conductance is delicate, and it is difficult to determine the adhesion of the particles. In comparison with this, according to the configuration of each of the above embodiments, the detection gas is introduced into the surrounding vacuum atmosphere to pressurize the gap, and the change in conductance is detected from the change in the amount of gas leakage at that time. Change is clearly visible. Therefore, it is easy to determine the adhesion of particles.

In each of the above embodiments, the detection gas is
It may be used also as a heat exchange gas for improving the heat exchange efficiency between the electrostatic suction stage 4 and the substrate 9.
For example, it is preferable to introduce a gas having a high heat transfer coefficient, such as helium, as the detection gas, because it is possible to detect the adhesion of particles and to improve the efficiency of controlling the temperature of the substrate.
The substrate 9 may be controlled in temperature while being cooled via the electrostatic suction stage 4 in addition to the heating by the heater 44.

In the above description, a sputtering apparatus is taken as an example of a substrate processing apparatus.
D) The concept of the present invention can be similarly applied to other substrate processing apparatuses such as an apparatus and an etching apparatus. As a method of electrostatic attraction, a plurality of pairs of attraction electrodes may be used.
In some cases, the electrostatic attraction is performed using the self-bias voltage described above. In this case, a high-frequency voltage is applied to one or more suction electrodes, and the dielectric block is dielectrically polarized by the self-bias voltage. The concept of detecting the adhesion of particles to the stage based on a change in conductance between the substrate 9 and the stage is not limited to the case of the electrostatic suction stage 4, and the concept of detecting a particle other than the electrostatic suction stage 4 (static It is also applicable to a stage where electroadsorption is not performed.

[0070]

As described above, according to the first or sixth aspect of the present invention, a simple and extremely practical configuration for detecting the adhesion of particles on the electrostatic attraction stage is provided. According to the second or eighth aspect of the present invention, the necessity of particles can be automatically determined, so that cleaning is performed in an unnecessarily short cycle, and the productivity is reduced meaninglessly. Conversely, the problem that the cleaning cycle becomes too long and the electrostatic attraction force is reduced and a large number of particles are generated does not occur. Further, since the necessity of cleaning the surface of the electrostatic chuck stage is determined by detecting the change in the conductance of the gap between the electrostatic chuck stage and the substrate, the configuration is simple and extremely practical. According to the third, seventh or ninth aspect of the present invention, in addition to the above-described effects, a detection gas is introduced into a gap between the electrostatic suction stage and the pressure in the gap or a gas introduction path of the detection gas is measured. By doing so, the change in conductance is known, so that it is easier to determine whether particles are attached. According to the fourth or tenth aspect of the present invention, in addition to the above-described effects, it is possible to detect the adhesion of particles during the processing of the substrate, so that the adhesion of particles can be easily monitored at all times. According to the fifth or eleventh aspect of the present invention, in addition to the above-described effects, an effect is obtained that the consumption of the detection gas is small. According to the twelfth aspect of the present invention, in addition to the above-described effects, the detection gas is also used as the heat exchange gas, so that the configuration is suitable for heating or cooling the substrate via the electrostatic suction stage. Becomes

[Brief description of the drawings]

FIG. 1 is a schematic front view of a substrate processing apparatus according to a first embodiment of the present invention.

FIG. 2 shows a part of a sequence control program executed by a controller 8 for extracting a detection gas.

FIG. 3 is a diagram showing a detection gas introduction sequence and a transition of a measurement value of a pressure gauge 72.

FIG. 4 shows a part of a subroutine necessity determination program in a sequence control program executed by a controller 8;

FIG. 5 is a diagram illustrating a change in conductance due to adhesion of particles.

FIG. 6 is an extract of a part of a sequence control program provided in the apparatus of the second embodiment for determining whether to introduce a detection gas and determine whether cleaning is necessary.

7 is a diagram showing a gas introduction amount and a transition of a measurement value of a pressure gauge 72 when a detection gas is introduced according to a sequence control program shown in FIG.

FIG. 8 is a schematic front view showing a conventional substrate processing apparatus provided with an electrostatic suction stage 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing chamber 11 Exhaust system 2 Process gas introduction system 31 Target 32 Sputter power supply 4 Electrostatic adsorption stage 51 High frequency power supply 6 Anti-shielding shield 71 Detection gas introduction system 711 Valve 72 Pressure gauge 8 Controller 81 Computer unit 811 Processor 812 Storage part 9 Substrate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 21/205 H01L 21/205 F term (Reference) 4K029 BD11 CA05 EA00 FA09 JA01 4K030 GA02 KA39 LA15 5F031 HA16 HA19 JA31 JA51 MA28 MA29 MA32 PA23 PA26 5F045 AA19 BB14 EB02 EB05 EE04 EH01 EH19 EM05 EM07 EM09 GB06 GB15

Claims (12)

[Claims] In a substrate processing apparatus for performing a predetermined process on a substrate in a processing chamber, a method for detecting adhesion of particles to an electrostatic suction stage provided in the processing chamber, the method comprising: A method for detecting particle adhesion from a change in conductance of a gap between an electrostatic chuck stage and a substrate when the substrate is electrostatically chucked. 2. A substrate processing apparatus for performing a predetermined process on a substrate in a processing chamber, wherein the adhesion of the substrate to the electrostatic suction stage provided in the processing chamber is performed when the substrate is electrostatically suctioned to the electrostatic suction stage. A method for determining whether or not cleaning of an electrostatic attraction stage is required, wherein the method determines whether or not the surface of the electrostatic attraction stage needs to be cleaned by detecting a change in conductance of a gap between the electrostatic attraction stage and a substrate. 3. A gas for detection is introduced into a gap between the substrate and the electrostatic suction stage adsorbed on the electrostatic suction stage, and a pressure in the gap or a gas introduction path of the gas for detection is measured. 3. A method according to claim 1, wherein the change in conductance is known. 4. The method according to claim 1, wherein the detection gas is introduced such that the pressure in the gap or the gas introduction path is kept constant, and the number of repetitions of introduction and cutoff at that time or the total introduction amount is compared. 4. The method of claim 3, wherein the change in conductance is known. 5. A change in the conductance is obtained by introducing a predetermined amount of the detection gas into the gap and comparing the time until the pressure in the gap or the gas introduction path falls to a predetermined lower pressure limit. 4. The method according to claim 3, wherein the information is known. 6. A processing chamber evacuated by an exhaust system, a gas introduction system for introducing a predetermined processing gas into the processing chamber, and a substrate to be processed being electrostatically attracted to a predetermined position in the processing chamber. Claims 1. A substrate processing apparatus comprising: an electrostatic chuck stage for holding, wherein particles from the change in the conductance of a gap between the electrostatic chuck stage and the substrate sucked by the electrostatic chuck stage cause particles to move to the electrostatic chuck stage. A substrate processing apparatus comprising a detecting unit for detecting the adhesion of a substrate. 7. A detecting gas introducing system for introducing a detecting gas into a gap between the substrate adsorbed on the electrostatic suction stage and the electrostatic suction stage, and a detecting means for detecting the gap. 7. The substrate processing apparatus according to claim 6, further comprising a pressure gauge for measuring a pressure in a gas introduction path of the introduction system, and a comparison unit for comparing a measured value of the pressure gauge with a predetermined reference value. 8. A processing chamber evacuated by an exhaust system, a gas introduction system for introducing a predetermined processing gas into the processing chamber, and a substrate to be processed electrostatically adsorbed to a predetermined position in the processing chamber. An electrostatic suction stage for holding;
A substrate processing apparatus comprising: a cleaning unit that cleans a surface of an electrostatic suction stage, wherein the cleaning is performed based on a change in a conductance of a gap between the substrate and the electrostatic suction stage that is suctioned by the electrostatic suction stage. A substrate processing apparatus comprising: a determination unit configured to determine whether cleaning is required by the unit. 9. A detecting gas introducing system for introducing a detecting gas into a gap between the substrate attracted to the electrostatic suction stage and the electrostatic attracting stage, and the gap or the detecting gas. 9. The substrate processing apparatus according to claim 8, comprising a pressure gauge for measuring a pressure in a gas introduction path of the introduction system, and a comparison unit for comparing a measured value of the pressure gauge with a predetermined reference value. 10. A controller for controlling the detection gas introduction system is provided, and the controller controls the detection gas introduction system so that the pressure in the gap or the gas introduction path is kept constant. 10. The substrate processing apparatus according to claim 7, wherein the comparison unit compares the number of repetitions of introduction and cutoff of the detection gas or the total amount of introduction at that time. 11. 11. A controller for controlling the detection gas introduction system, wherein the controller controls the detection gas introduction system so that a certain amount of the detection gas is introduced into the gap. 10. The substrate processing apparatus according to claim 7, wherein the comparing unit compares the time until the pressure in the gap or the gas introduction path falls to a predetermined lower pressure limit. . 12. The detection gas introduced by the detection gas introduction system is also used as a heat exchange gas for improving heat exchange efficiency between the electrostatic suction stage and the substrate. The substrate processing apparatus according to claim 7, 9, 10, or 11, wherein